In December 2011, I assisted seabird expert Graeme Taylor with his work on the migration of Buller’s Shearwaters. This species of petrel breeds only on the Poor Knights but there are massive numbers there, and in the breeding season they are a common coastal bird all around New Zealand. Graeme had attached geologgers to birds’ legs in March and needed to recapture these individuals to retrieve the data from the little devices. When we retrieved geologgers, Graeme could download the information onto his laptop in the field, so straightaway we could see the amazing journey that these birds take in their non-breeding season – firstly east of New Zealand, then rapidly north across the equator to east of Japan, then across to the North American west coast before shooting back southwest to the Poor Knights. This mammoth trip is an annual event for each bird but until now the precise route of the migration was unknown.

A geologger on a Buller's shearwater's leg will record its migration around the Pacific. Photo Alan Tennyson, Te Papa

Like most petrels, Buller’s Shearwaters nest in rabbit-like burrows and are active on the breeding grounds only at night, so we spent most of our time with our arms down holes or searching the ground for birds at night. This gave us an opportunity to see how the islands transform from being a quiet coastal forest environment by day to a place teeming with night life. Many species of weta, giant centipedes, Placostylus snails, tuatara, numerous lizards, as well as the ever present shearwaters, only show themselves at night.

The giant land snail Placostylus hongii is common on the Poor Knights. Photo Alan Tennyson, Te Papa

The Poor Knights are special for two key reasons: (1) they remained isolated from mainland New Zealand during the last glaciation (so have been islands for 10,000s of years) – this led to the evolution of many unique forms of plants and animals; (2) rats, cats, stoats, and other predatory mammals, never became established, so the biota has survived human modifications largely intact.

It’s only when you visit a place like the Poor Knights that you understand what New Zealand was like before human times.